Trekking safari in Botswana?

I'm planning a trip to Botswana with my brother in the first half of August this year. We are both excited about the wilderness and relatively unexploited national parks we expect to find there. What has really caught our interest is the trekking safaris, optionally including canoeing. I believe a safari of three to six days would suit us perfectly. We are not interested in any luxury camps. Rather, cooking our own meal by the fire outside a simple tent would add to the experience that we are looking for. Do you know where they do trekking safaris?